Hacker News Reader

Comment by falcrist | Hacker News Reader

There's actually a parity to the positions of the pieces that most people don't seem to know about. If you flip an edge or twist a corner, the whole cube becomes unsolvable.

You can also make it unsolvable by swapping stickers because each piece is unique. There is only one red/white/blue corner and only one green/yellow edge. Assuming standard color arrangement, there is no piece with both yellow and white, or both blue and green, or both red and orange.

View on HN

The guy I learned to speedcube from was so good that we would secretly flip a corner or edge on his cube, challenge him to a race, and he would solve it to the point where only one piece was flipped, curse at us, fix it himself, and still beat us all by at least 10 seconds.

Depending on his method, he probably saw the problem immediately when he got to the last layer.

Yep, it would be readily apparent by that point. You wouldn't even need to "solve" it first; you would see pretty much instantly that the last layer was in an impossible position.

Source: I got into speedcubing for a couple years in high school and averaged in the 30s, with a record of 26 seconds.

This is absolutely true. I believe he was at least using ZLL at that time, so it only took him 10-15 seconds to figure it out.

A friend of mine got into a Rubik’s Cube in college. As a prank, we swapped the stickers on his cube and were amazed when he noticed it in a few seconds and correctly identified what was swapped. Familiarity with the invariants

Reply on news.ycombinator.com